Difference between revisions of "Aspergillosis"

Revision as of 11:20, 17 August 2010

Description

Aspergillosis is a disease of the respiratory system caused by several Aspergillus spp. A. fumigatus is the most frequently reported species in domestic animals. Commonly affected species include birds, dogs, cats, horses and cattle but the disease has been reported in many other wild and domestic species.

Clinical signs and features

Birds

In avian species the disease manifests as a diffuse infection of the air sacs. Two forms of the disease have been reported; a diffuse pneumonic form and a nodular form involving the lungs. Clinical signs include diarrhoes, listlessness, pyrexia, loss of appetite and loss of condition. Seizures may occasionally occur.

Aspergillus in a swan
^{Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath}

Cattle

Infection in cattle may cause abortion and ocular infections. Infections involved the uterus, foetal membranes and foetal skin. Lesions are usually up to 2mm in diameter and contain asteroid bodies with a germinated spore in the centre. Acute infection causes miliary lesions and chronic infections causes granulomatous and calcified lesions.

Horses

In the horse the guttural pouches are most commonly affected. Aspergillus infection may also lead to abortion.

Dogs

Aspergillosis is a common cause of nasal disease in dogs. Young to middle aged male dogs are most commmonly affected but animals of all age and of both sexes may be affected. The disease is usually localised to the paranasal sinuses and nasal cavity but a disseminated form with granulomas and infarcts has been reported in dogs. Pulmonary and intersitital forms may also occur in cats.

Aspergillus in vivo
^{Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath}

Diagnosis

Grows on Sabauraud's Dextrose and Blood agar
- White colonies intitially which turn green, then dark green, flat and velvety
- Colony colour varies with species

Also grows on Czapek-Dox agar and 2% malt extract agar supplemented with antibacterial antibiotics

Microscopically:
- Conidiophores with large terminal vesicles (only visible in the lungs and air sacs where there is access to oxygen)
  - Vesicle shape varies depending on the species
- Is a common contaminant so repeated tests should be done for a definitive diagnosis

Serology:
- Gel immunodiffusion for canine nasal asper

Treatment:
- Surgery
- Antifungal drugs
  - Ketoconazole, Nystatin, Amphotericin B, 5-fluorocytosine, Thiabendazole

Pathology:
- Aspergillus fumigatus causes rhinitis, respiratory tract inflammation and sinusitis
- Sometimes appears on lesions of ethmoidal haematoma

Aspergillus sporing heads
^{Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath}
Aspergillus mycelium stained with blue/black Quink
^{Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath}
Mycotic Abortion caused by Aspergillus
^{Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath}
Mycotic Abortion caused by Aspergillus
^{Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath}
Mycotic Abortion caused by Aspergillus
^{Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath}
Nasal Aspergillus
^{Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath}
Canine nasal aspergillus radiograph
^{Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath}

Aspergillus fumigatus

Aspergillus hyphae in cattle lung (Image sourced from Bristol Biomed Image Archive with permission)

Nasal aspergillosis (Image sourced from Bristol Biomed Image Archive with permission)

@@ Line 5: / Line 5: @@
 Aspergillosis is a disease of the respiratory system caused by several [[Aspergillus]] spp. A. fumigatus is the most frequently reported species in domestic animals. Commonly affected species include birds, dogs, cats, horses and cattle but the disease has been reported in many other wild and domestic species.
-==Clinical signs==
+==Clinical signs and features==
 ===Birds===
@@ Line 21: / Line 21: @@
 In the horse the guttural pouches are most commonly affected. Aspergillus infection may also lead to abortion.
-===Dogs, cats and sheep===
+===Dogs===
-Infections occur, but infrequently in these animals. The lungs and nasal cavity are most commonly affected. Dogs
+Aspergillosis is a common cause of nasal disease in dogs. Young to middle aged male dogs are most commmonly affected but animals of all age and of both sexes may be affected. The disease is usually localised to the paranasal sinuses and nasal cavity but a disseminated form with granulomas and infarcts has been reported in dogs. Pulmonary and intersitital forms may also occur in cats.
-**Disseminated form with granulomas and infarcts can occur in dogs
-**Pulmonary and intersitital forms can occur in cats
 {| align="right"
 |<gallery>Image:Aspergillus in vivo.jpg|<center><p>'''Aspergillus in vivo'''</p><sup>Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath</sup></center></gallery>
 |}
-*Humans:
+==Diagnosis==
 *Grows on Sabauraud's Dextrose and Blood agar
@@ Line 66: / Line 69: @@
 [[Image:Aspergillus pneumonia of cattle.jpg|right|thumb|100px|<small><center>Aspergillus hyphae in cattle lung (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
 [[Image:Aspergillosis in nasal cavity.jpg|right|thumb|100px|<small><center>Nasal aspergillosis (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
-*[[Aspergillus spp.|''Aspergillus fumigatus'']]
-*Most commonly in dogs but also other species
-*Causes [[Nasal Cavity Inflammatory - Pathology#Infectious causes of rhinitis|rhinitis]], often also involves the [[Paranasal Sinuses Inflammatory - Pathology#Infectious causes of sinusitis|frontal sinus]]
-*Chronic necrotising inflammation with friable exudate containing necrotic tissue and fungal hyphae
-* Result in severe neutrophilic [[Nasal Cavity Inflammatory - Pathology|rhinitis]]/[[Paranasal Sinuses Inflammatory - Pathology|sinusitis]]
-*These lesions can be aggressive causing destruction of turbinates and nasal septum
-*Can occur secondary to areas of mucosal compromise eg: adjacent to a space-occupying lesion
-*Can cause pulmonary aspergillosis especially in '''birds''', but also other animals
-**Initiated by inhalation of spores,the most likely source of which is mouldy feed and bedding
-**Given the wide exposure that occurs, it is thought that immunodeficiency may contribute to colonisation with this organism
-**Gross lesions :
-***Multiple discrete grey/ white nodules which develop around fungal colonies
-***Blood vessels can become involved in the lesions -> invasion, haemorrhage or thrombosis
-**Histologically:
-***Granulomatous chronic lesions
-***Macrophages and epithelioid cells
-***Fibrous capsule
-*In horses:
-**[[Nasal Cavity Inflammatory - Pathology#Infectious causes of rhinitis|Nasal aspergillosis]]
-**[[Guttural Pouches Inflammatory - Pathology|Guttural pouch infections]] in horses - fungal plaques form on the adventitia of the carotid arteries can lead to catastrophic haemorrhage following erosion of carotid arteries!
-**Often present with [[Respiratory System Clinical Signs - Pathology#Epistaxis|epistaxis]]
-**May present with neurological dysfunction
-**Rarely extends to other resions: cranium, middle ear, atlanto-occipital joint
-**May extend to [[Paranasal Sinuses Inflammatory - Pathology#Infectious causes of sinusitis|sinuses]]